查找使用阿拉丁产品的科研文献

Optimization of the Selenization Pressure Enabling Efficient Cu2ZnSn(S,Se)4 Solar Cells

Hongling Guo,Rutao Meng,Long Hu,Chun-Ho Lin,Yali Sun,Yue Liu,Jianyu Wu,Zhan Shen,Dewei Chu,Gang Wang,Li Wu,Guangxing Liang,Shifu Xiong,Fangfang Liu,Yi Zhang,Tom Wu

In spite of the merits such as Earth abundance and high performance, Cu 2 ZnSn(S,Se) 4 (CZTSSe) solar cells suffer from unfavorable Sn Zn antisite defects and complexes, which act as nonradiative recombination centers and deteriorate the open-circuit voltage ( V OC ). Therefore, the management of Sn composition is the prerequisite for achieving high-efficiency CZTSSe photovoltaic devices. At present, the Sn-related composition and defect modifications at different selenization pressures remain unclear, which restrain the development of efficient kesterite solar cells. Herein, a facile yet effective strategy to accurately adjust the Sn content in CZTSSe films by simply optimizing the selenization pressure is demonstrated. Compared with the widely used atmospheric pressure, it is unveiled that the appropriate negative pressure (0.7 atm) can tailor the optimal Sn content in the absorber layer, influencing both the Sn-related defects and the microstructures. In contrast, a lower (0.4 atm) and a higher (1.3 atm) selenization pressure results in undesirable deep Cu Sn defects and a Sn(S,Se) 2 secondary phase, respectively. A champion device fabricated at this optimal selenization pressure (0.7 atm) exhibits a power conversion efficiency of 11.32% with a V OC of 0.496 V. This study paves the path toward highly efficient kesterite solar cells by tailoring the composition-dependent defects.

Tuning the Band Gap of Cu2ZnSn(S,Se)4 Thin Films via Lithium Alloying

Yanchun Yang,Xiaojiao Kang,Lijian Huang,Daocheng Pan

Alkali metal doping plays a crucial role in fabricating high-performance Cu(In,Ga)(S,Se)2 and Cu2ZnSn(S,Se)4 (CZTSSe) thin film solar cells. In this study, we report the first experimental observation and characterizations of the alloyed LixCu2–xZnSn(S,Se)4 thin films. It is found that Cu+ ions in Cu2ZnSn(S,Se)4 thin films can be substituted with Li+ ions, forming homogeneous LixCu2–xZnSn(S,Se)4 (0 ≤ x ≤ 0.29) alloyed thin films. Consequently, the band gap, conduction band minimum, and valence band maximum of LixCu2–xZnSn(S,Se)4 thin films are profoundly affected by Li/Cu ratios. The band alignment at the LixCu2–xZnSn(S,Se)4/CdS interface can be tuned by changing the Li/Cu ratio. We found that the photovoltaic parameters of the LixCu2–xZnSn(S,Se)4 solar cell devices are strongly influenced by the Li/Cu ratios. Besides, the lattice constant, carrier concentration, and crystal growth of LixCu2–xZnSn(S,Se)4 thin films were studied in detail.

Enhancing electrical properties of Cu2ZnSn(S,Se)4 thin films via trace Co incorporation

Jingying Zhang,Yanchun Yang,Guonan Cui,H. Alata,Yiming Wang,Chengjun Zhu

Substitution of Zn 2+ ionic by Co 2+ ionic is known to suppress the cation disorder of Cu 2 ZnSn(S,Se) 4 thin films , which is helpful to obtain the excellent Cu 2 ZnSn(S,Se) 4 solar cell devices. In our work, the extra trace Co incorporation was added in the solution without affecting the compositions of other elements (i.e. Cu, Zn, and Sn) to enhance the electrical properties of Cu 2 ZnSn(S,Se) 4 thin films . And Co incorporation does not enter into the lattice nor be found in the selenized films after taking effect, but increases the crystallinity , compactness, carrier concentration, and electrical properties of Cu 2 ZnSn(S,Se) 4 thin films samples. By tuning the doping ratios of Co 2+ ionic, the surface roughness of the selenized films can be decreased from 110.2 nm (0 mol %) to 68.90 nm (5 mol %). As 1 mol % of Co 2+ ionic is doped, the carrier concentration of films can be also improved to 4.35 × 10 17  cm −3 from 2.63 × 10 16  cm −3 , and average surface current of films applied 1 V AC voltage can be increased from 2.426 nA to 4.454 nA. The enhanced properties of Co-incorporated films brings hope for the excellent performance of Cu 2 ZnSn(S,Se) 4 solar cells.

Enhancing the efficiency of Cu2ZnSn(S,Se)4 solar cells by variable-temperature sulfoselenization

Yonggang Zhao,Congyan Xu,Zhineng Zhou,Yufei Chen,Ying Zhang,Lang Wu,Xu Su,Xinghuan Hu,Shurong Wang

High-temperature sulfoselenization is essential in producing Cu2ZnSn (S,Se)4 (CZTSSe) thin-film solar cells. At high temperature, the Cu2ZnSn(S,Se)4 phase-transition speed is fast, which causes grain transition to mature quickly, followed by grain decomposition. Although grain surfaces are relatively flat at low temperatures, the small grain and more grain boundaries lead to low efficiency. In this study, a dynamic-temperature sulfoselenization process was adopted to utilize both the advantages of high and low temperatures comprehensively. Different constant- and variable-temperature sulfoselenization processes were developed for annealing Cu–Zn–Sn–S precursor films prepared in the air using dimethyl sulfoxide (DMSO) and 2-methoxyethanol (MOE) dual solvent systems. As a result, CZTSSe films with a flat, holeless, and dense surface, and a single-layer large grain penetrating the whole cross-section were fabricated by a proper variable-temperature sulfoselenization process. Finally, 11.11% total-area power conversion efficiency (12.22% active area efficiency) of CZTSSe solar cells (without antireflection coating) based on the variable-temperature sulfoselenization process was achieved successfully. Compared with the highest efficiency of 9.10% of CZTSSe film solar cells fabricated from the stable-temperature sulfoselenization annealing process, the efficiency was improved by 22%. The variable-temperature annealing processes in this study can also be applied to the preparation of other multi-element thin-film semiconductor materials.

Phase-Separation-Induced Crystal Growth for Large-Grained Cu2ZnSn(S,Se)4 Thin Film

Lijian Huang,Song Wei,Daocheng Pan

Large-grained Cu2ZnSn(S,Se)4 (CZTSSe) absorber layers are highly desirable for high-performance CZTSSe thin film solar cells. However, solution-deposited CZTSSe thin films usually consist of a large-grained top layer and a smaller-grained bottom layer. In this work, we adopt a phase-separation strategy to promote the crystal growth of the CZTSSe thin film. By choosing ZnCl2, SnCl2, CuCl (instead of CuCl2), and thiourea as the starting materials, a Cu2S/SnS/ZnS hybrid precursor thin film can be prepared, the composition of which has been testified by X-ray diffraction, X-ray photoelectron spectroscopy, Raman, and scanning electron microscopy-energy-dispersive spectrometry characterization. Owing to the volume expansion caused by Se incorporation and the high migration abilities of Cu(I) and Sn(II) ions during selenization, large-grained and compact CZTSSe films with a thickness up to 5 μm can be obtained. The corresponding thin film solar cell devices have achieved active power conversion efficiencies above 10% (8.78% for total area), much higher than those of CuCl2-based CZTSSe devices in our lab.

Above 10% efficient electrodeposited Cu2ZnSn(S,Se)4 solar cell achieved by modifying precursor

Xiatong Qin,Bin Xu,Jianjun Lin,Jiaqi Chen,Hanyu Tong,Ye Chen,Pingxiong Yang,Junhao Chu,Lin Sun

Electrodeposition is a promising method to fabricate Cu 2 ZnSn(S,Se) 4 (i.e., CZTSSe) absorber layer thanks to its many advantages such as low-cost and large-scale. However, the secondary phases and intrinsic defects in electrodeposited CZTSSe solar cells inevitably limit the photoelectric performance. Herein, two different kind of precursor films (binary-ternary selenide vs. quaternary selenide) are deliberately fabricated and the effect of these precursors on the secondary phases and intrinsic defects of CZTSSe absorber layer are investigated comprehensively. The absorber layer obtained from binary-ternary selenide precursor has a small amount of ZnSe secondary phases and Cu Sn deep defects , whereas that obtained from the quaternary selenide precursor exhibits the favorable V Cu shallow defects, which is beneficial to the efficiency improvement in CZTSSe. Based on the quaternary selenide precursor film, the CZTSSe solar cell with 10.03% total area efficiency (the active area efficiency is 10.9%) was obtained. This is the highest efficiency of CZTSSe solar cells prepared by the electrodeposition method.

Optimizing the window layer for achieving over 10% efficient Cu2ZnSn(S,Se)4 solar cells

Yu He,Chenxi Zhao,Zecheng Lu,Ning Guo,Hongmei Luan,Yanchun Yang,Ruijian Liu,Chengjun Zhu

Indium tin oxide (ITO) and intrinsic ZnO (i-ZnO) are usually used as the window layer of Cu 2 ZnSn(S,Se) 4 (CZTSSe) solar cells within a typical structure. The optoelectronic properties of the window layer play a crucial role in determining the efficiency of solar cells. In this work, two types of CZTSSe solar cells with and without i-ZnO layers were fabricated using dimethyl sulfoxide (DMSO) and dimethylformamide (DMF) as solvents, respectively. The impact of the window layer on the performance of CZTSSe solar cells was investigated. The results suggest that the device without i-ZnO still exhibits a high power conversion efficiency (PCE) compared to conventional bilayer i-ZnO/ITO structures. By removing i-ZnO and optimizing the thickness of ITO, the highest power conversion efficiency (PCE) of DMSO and DMF-based CZTSSe solar cells has been up to 10.17% and 10.27%, respectively, with an increase in open-circuit voltage (V OC ) of 15 mV (in DMSO system) and 10 mV (in DMF system), as well as an enhancement in fill factor (FF) by ∼5 percentage points. These performance improvements are mainly attributed to the reduction of series resistance (R s ) of the window layer due to the removal of i-ZnO layer. Further analysis shows that the generation and collection of photon-generated carriers in CZTSSe solar cells can be affected by the optimized window layer due to optical interference effects and its resistance. Our research may provide insights for the preparation of high efficient CZTSSe solar cells with new structures of the i-ZnO free window layer.

MoO2 Sacrificial Layer for Optimizing Back Contact Interface of Cu2ZnSn(S,Se)4 Solar Cells

Bin Xu,Xiaoshuang Lu,Chuanhe Ma,Yulin Liu,Ruijuan Qi,Rong Huang,Ye Chen,Pingxiong Yang,Junhao Chu,Lin Sun

Fabrication and photoelectric properties of Cu2FeSnS4(CFTS) and Cu2FeSn(S,Se)4(CFTSSe) thin films

Shuo Wang,Ruixin Ma,Chengyan Wang,Shina Li,Hua Wang

This report details the development of a simple, non-vacuum, mild route for the fabrication of CFTS and CFTSSe thin films. This work investigates the synthesis of CFTS powder using solid-phase synthesis. Subsequently, the stable colloidal ink was prepared and blade-coated onto Mo-coated substrates followed by an annealing process under an Ar atmosphere. Thin films of this material were converted into CFTS and CFTSSe thin films by sintering and exposing them in sulfur or selenium vapor. The structures of the CFTS and CFTSSe were observed to be consistent with the stannite phase. The crystal lattice parameters of the CFTS and CFTSSe post-annealed films were determined by their respective X-ray diffraction patterns and Raman scattering measurements. The band gaps of CFTS and CFTSSe films, as determined by UV–vis absorption, were estimated to be 1.32   eV and 1.22   eV with an error of ±0.02   eV. The corresponding CFTS and CFTSSe films showed a clear photoresponse without current transients, which is promising for future photovoltaic applications.

Efficient flexible Mo foil-based Cu2ZnSn(S, Se)4 solar cells from In-doping technique

Xue Yu,Shuying Cheng,Qiong Yan,Junjie Fu,Hongjie Jia,Quanzhen Sun,Zhiyuan Yang,Sixin Wu

Cation substitution has an important impact on the power conversion efficiency (PCE) of Cu 2 ZnSn(S,Se) 4 (CZTSSe) solar cells. Herein, a significant PCE enhancement of flexible indium-doped CZTSSe solar cells has been achieved by partially substituting Sn 4+ with In 3+ . Systematic measurements indicate that In doping in CZTSSe film effectively improves the crystallinity and carrier concentration of the absorber layer . Meanwhile, the treatment reduces interface recombination and band tailing by passivating deep defects and increases the open-circuit voltage ( V oc ) of the solar cells. By physical analysis, the key parameters for the solar cell diode such as A , J 0 , R s and R sh are significantly improved after In-doping, indicating better PN junction quality. Under the optimal In-doping (x = In/(Sn + In) = 9%), the flexible Cu 2 ZnSn 1- x In x (S,Se) 4 solar cell has been successfully obtained with the best efficiency of 7.19% and the V oc enhancement of 62 mV due to reduced V oc deficit and band tailing.

Improving the Performance of Solution-Processed Cu2ZnSn(S,Se)4 Photovoltaic Materials by Cd2+ Substitution

Jie Fu,Qingwen Tian,Zhengji Zhou,Dongxing Kou,Yuena Meng,Wenhui Zhou,Sixin Wu

Additional elements in the Cu2ZnSn(S,Se)4 (CZTSSe) absorber layers can play a crucial role in improving the performance of thin film solar cells. In this paper, a significant performance enhancement of CZTSSe thin film solar cells was achieved by the partial substitution of the Zn2+ cation with Cd2+. A small amount of Cd2+ can be successfully incorporated into the host lattice of CZTSSe to form a homogeneous Cu2Zn1–xCdxSn(S,Se)4 (CZCTSSe) alloy material. We demonstrated that the crystal growth and the band gap of CZCTSSe thin films are affected by the Cd doping level. Additionally, the impact of Cd content on the space-charge density (Nc-v) and the depletion width (Wd) of CZCTSSe solar cells was systematically investigated. By this cation substitution approach, the power conversion efficiency of the solar cells based on the CZCTSSe absorber was successfully increased from 5.41 to 8.11% for the optimal composition (x = 5%).

Fabrication of a Cu2ZnSn(S,Se)4 Photovoltaic Device by a Low-Toxicity Ethanol Solution Process

Gang Wang,Wangen Zhao,Yong Cui,Qingwen Tian,Shang Gao,Lijian Huang,Daocheng Pan

Homogeneous molecular precursor solutions are excellent choices for obtaining smooth absorber layers, and they offer the potential to significantly lower the manufacturing cost of solar cells. Here, we present a thermally degradable metal butyldithiocarbamate-based solution approach to fabricate Cu2ZnSn(S,Se)4 solar cells. Low-cost Cu2O, ZnO, and SnO were used as the starting materials and were dissolved in the ethanol solution of butyldithiocarbamic acid. By tuning the composition of the Cu2ZnSn(S,Se)4 thin film, a power conversion efficiency of 6.03% on the basis of the active area has been achieved.